The methylenebis derivative of nu-carbamylmaleimide



United States Patent THE METHYLENEBIS DERIVATIVE OF N-CARBAMYLMALEIMHBEPliny 0. Tawney, Passaic, and Robert J. Kelly, Clifton,

N. J., assignors to United States Rubber Company, New

York, N. Y., a corporation of New Jersey No Drawing. Application October27, 1954, Serial No. 465,138

1 Claim. (Cl. 260-326.3)

This invention relates to preparation of a new chemical,

denoted methylenebis-(N-carbamylmaleimide) represented by the formulaAccording to the aforementioned copending application Serial No.367,108, the N-carbamylimides are derived from the interaction of anN-carbamylamic acid and an acid anhydride of a saturated aliphaticmonocarboxylic acid having from two to four carbon atoms; i. e., anoncyclic acid anhydride. The reaction for making the specificN-carbamylimide used in our invention, N-

carbamylmaleimide, is represented as follows:

H NCO-NH; RIC/OOH RzCOOH where each of R1 and R2 is an alkyl radicalhaving not more than three carbon atoms.

The preferred method of making N-carbamylmaleimide is as follows. TheN-carbamylmaleamic acid is made in any known manner, but preferably bythe method out- 2,745,841 Patented May 15, 1956 2 lined in copendingapplication of Snyder, Serial No. 312,869, filed October 2, 1952.

A mixture of 50 parts of N-carbamylmaleamic acid and 120 parts ofglacial acetic acid is heated to about C., 50 parts of acetic anhydrideis added gradually to the stirred mixture, which is held at the sametemperature until practically all of the suspended N-carbamylmaleamicacid has disappeared. The hot solution is filtered, and cooled to roomtemperature, causing crystallization of a white product.

This material, N-carbamylmaleimide, melts at 157158 C. The yield is 41parts (92.5% of theory).

The N-carbamylmaleimide made according to the foregoing description isthen reacted with paraformaldehyde or formalin to prepare themethylenebis-(N-carbamylmaleimide) according to our invention. Thefollowing example will illustrate the preparation of themethylenebis-(N-carbamylmaleimide) in detail.

Example 1 Concentrated sulfuric acid (3600 g.) was cooled to 5 C.N-carbamyhnaleimide (840 g.) was added very slowly, with stirring, theaddition taking about A of an hour. With the temperature still near -5C., paraformaldehyde g.) was added slowly with stirring over afifteen-minute period. Stirring was continued at 0 C. for 2 hours, afterwhich the entire batch was quenched in 9000 g. of an ice and watermixture and filtered immediately. The filter cake was washed three timeswith ice water and then set aside to air-dry. The melting point of thisdried crude material was ca. 170 C. The entire product (345 g.) washeated to C. with 4000 g. of acetic acid and 400 g. of acetic anhydrideto dissolve it; then filtered and set aside to cool. The recrystallizedmaterial was then filtered off. The yield was 205 g. (22% of theory) ofmethylenebis-(N-carbamylmaleimide) which melted at 2l22l4 C.

Analysis: 7

Calcd. for C11HsOflN4 Fwnd .percent. 45. 2 45. 53 do 2. 76 2.92 do 19. 118. 50 Neutral Equivalent 146. 0 146.8

Example 1 represents the preferred method of making themethylenebis-(N-carbamylmaleimide) from N-carbamylmaleimide, i. e., bythe use of paraformaldehyde rather than formalin or otherformaldehyde-yielding material, and by recrystallizing the product fromacetic acid after washing with ice water. The use of formalin is lessdesirable because of the substantial evolution of heat and consequentraising of the temperature of the reactant mixture. This leads to aconsiderable amount of side reaction, hence lowering the yield of thedesired product. Acetic acid has been found to be the bestrecrystallizing agent for the compound, although other materials, dioxanfor example, may be used for this purpose. However, washing and/orrecrystallizing with dioxan leads to molecular addition productcontaining a mole-for-mole ratio of dioxan and themethylenebis-(N-carbamylmaleimide).

Methylenebis-(N-carbamylmaleimide) is useful as an intermediate inmaking N-carbamylmaleamate esters, which in turn are useful in makingcasting resins, and protective coatings and films, as shown in thefollowing examples.

Example 2 A mixture of 5.84 g. of methylenebis-(N-carbamylmaleimide), 50ml. of methanol and 0.27 g. of zinc chloride was refluxed on a steambath for 2 hours. The hot solution was filtered to remove a littleunreacted material. The filtrate was cooled to cause the white product,methylenebis-(methyl N-carbamylmaleamate) to crystallize. The yield was4.9 g. It melted at 1679 C. After recrystallization from water it meltedat 17 -1 C. .(with decomposition).

Analysis:

Caled. for wound e g gfg (percent) Carbon 43. 7 44. 06 Hydrogen 4. 48 4.55 Nitrogen. 15. 63 15. 69

Example 3 A mixture of 5.84 g. of methylenebis-(N-carbamyl maleimide),35.2 g. of n-butanol and 0.27 g. of zinc chloride was heated on a steambath for 3 hours. The white product, methylenebis-(n-butylN-carbamylmaleamate) was separated as shown in Example 2. The yield was2.73 g. It melted at 115-7 C. After recrystallization from methanol itmelted at 1l9.5120.5 C.

Analysis:

Calcd. for u T ound 06105132 23 5 4 (percent) Example 4 Calcd. for

Found gagg (percent) Carbon 63. 3 63. 35 Hydrogen 9. 10 9. 08 Nitrogen8. 43 8. 12

Example 5 A stirred mixture of 10.0 g. ofmethylenebis-(N-carbamylmaleimide), 3.56 g. of freshly distilledpentaniethylene glycol, 100 ml. of nitromethane and 0.1 g. of zincchloride was heated on a steam bath for 7.5 hours. The originally clearyellow solution began depositing a solid material Within the first 2hours heating. Additional solid appeared throughout the heating. Thesupernatant liquid then was decanted. The yellow solid was washed withmethanol and then with ether. A second crop of the yellow solidseparated from the cooled supernatant nitromethane solution. Both cropssoftened and partially melted at about -100 C. The first crop was driedthoroughly in vacuo, and analyzed.

Analysis:

Calcd for 1:1

Found ggfig (percent) 48. 4 48. 23 Hydrogen. 5. 08 5. 29 Nitrogen 14. 0513. 73

Intrinsic viscosity, in dimethyl formamide, was 0.10.

It is evident that methylenebis-(N-carbamylmaleimide) and pentamethyleneglycol reacted equimolecularly to form a long-chain,poly-(N-carbamylmaleamate) wherein the two reagents alternate with eachother in forming the chain.

The formation of the N-carbarnylmaleamate esters shown in Examples 2-5is analogous to the formation of N-carbamyhnaleamate esters fromN-carbamylmaleimide and non-tertiary alcohols. The latter reaction isdescribed in detail in a copending application of Snyder and Tawney,Serial No. 395,281, filed November 30, 1953. The use of zinc chloride toaccelerate the formation of such esters is shown in Tawney copendingapplication, Serial No. 395,283, filed November 30, 1953.

The esters of Examples 25 can be homopolymerized or copolymerized in thepresence of a free-radical source, e. g., an organic peroxide orhydroperoxide, N,N-azobis- (isobutyronitrile) or ultra violet light, toform useful casting resins. The comonomers used in making copolymers arethose which have one or more vinyl groups, CH=CH2, e. g., styrene, vinylacetate, etc. The polymers, and particularly the copolymers, also areuseful as protective coatings and films which are insoluble andinfusible. The polymerization reactions are analogous to those describedin Tawney copending application, Serial No. 395,282, filed November 30,1953, wherein the polymerization of N-carbamylmaleamate esters made fromN-carbamylmaleimide is shown. However, all of thernethylenebis-(N-carbamylmaleamate) esters can form insoluble, infusibleresins on homopolymerization or co polymerization with monovinylcompounds, whereas only the esters made from N-carbamylmaleimide and apolyhydric alcohol can form such resins.

Having thus described our invention, what we claim and desire to protectby Letters Patent is:

A compound represented by the formula No references cited.

